Paper-making.



Tans

ATENT OFFI E,

. WILLIAM S. COLGROVE, OF DOWLING, OHIO, ASSIGNOR OF ONE-FOURTH TOFREDERICK II. SOIIRODER, OF PEMBERVIIILE, OIllO.

PAPER-MAKING.

SPECIFICATION forming part of Letters Patent No. 643,084, dated February6, 1900.

Application filed September 8, 1898. Serial No. 690,502. (No specimens.)

To (tZZ whom, it may concern:

Be it known that-I, WILLIAM S. COLGROVE, a citizen of the United States,residing at Dowling, in the county of lVood and State of Ohio, haveinvented certain new and useful Improvements in Paper-Making; and I dohereby declare the following to be a f ull,clear, and exact descriptionof the invention, such as will enable others skilled in the art to whichit appertains to make and use the same.

This invention relates to the preparation of safety-paper to be used forbank-notes, bonds, checks, receipts, promissory notes, accounts, andother financial and commercial purposes; and its object is to preventthe fraudulent alteration by acids of such instruments.

Briefiystated,the invention consists in treating the rolls or sheets ofpaper to a bath of lye and soluble indigo weak enough to avoid dyeing orfurther bleaching the paper and drying them cold, after which theapplication to the paper of any of the acids used in the fraudulentalteration of printing or writing will discolor both surfaces of thepaper and so indelibly expose the fraud.

In the working ofthe invention I take soluble indigo and over it pour aquantity of woodash lye, the leach being of medium strength and aboutthe color of a weak infusion of tea while hot, and the proportion ofindigo kept down, so that it will not blue the mixture to ordinaryeyesight. The proportion of soluble indigo to Wood-ash in preparing themixture may be as low as one-twentieth and should not be more thanone-tenth, as-

' suming both to be in a solution of medium strength. The strength ofthe lye and the indigo in the solution is a simple matter of experienceand judgment and will vary according to the character of the paper to betreated, the test of proper strength being that the solution whenapplied to any roll or liquid is then ready for use and can be appliedto unmarketed paper at the factory, or

any bookbinder or printer can apply it to the sheets of paper needed tofillan order for Paper treated as above described is notstained,discolored, or in any other way injured or depreciated by mypreparation, nor is any such effect produced by the application of anykind of printing or writing ink; but any application of any kind of acidto one surface of the paper produces an irremovable stain on bothsurfaces and so exposes any attempt by means of acids to tamper with thewriting or printing already on the paper.

Concentrated lye maybe used in the preparation of the mixture Where/theuser does not desire to personally leach the wood ashes. The offic'e ofthe lye is to carry the soluble indigo, which is the discoloring-matter,into the texture of the paper and deposit it there ready to react andspread to and on the surface when reached by any acid applied to paper.

To better understand the nature and scope of myinvention, let it beassumed that I take four sheets of ordinary bank-check paper, eachtwenty two by twenty four inches, enough for one hundred ordinary'checkswith stubs. To treat those four signatures, as the sheets aretechnically called, I take one hundred and sixty pennyweights of commonwood-ash lyeof the color of a weak infusion of tea when hot. Into thisleach I put eight pennyweights of soluble indigo, preferably of akindcontaining anywhere from one to not more than five per centum ofgreen vitriol. After waiting the brief time necessary for the lye todissolve the indigo I expel the greenish sediment by filtering orstraining the solution. Then I place the solution in a clean, dry,broad, shallow vessel and separately dip and rapidly draw each signatureinto and through the solution, avoiding a soaking of the paper. Then Ieither blot the wet signature or sheet or run it between rollers, ineither. case keeping it under pressure till nearly dried, and'the finaldrying is effected by the atmosphere in or out of doors. Paper beingthus sensitized, it results that whenever any kind of acid is touched toeither surface of it a blue stain will come to each surface irregular inform and of alittle larger area' than that of the acid applied.

In actual working of my invention those using it maysometimes find itmost convenient to use some brand of commercial concentrated lye insteadof preparing the woodash leach for themselves. In such a case they Willhave to dilute the concentration with soft cold Water, their ownjudgment, experience, and a few actual trials teaching them how toprepare the dilution. Similarly it may be more convenient to use somebrand or another of package indigo as prepared for the market, providedit be soluble in alkali, and as to that I repeat the remark just made.

I do not claim the use of lye and indigo, or either, in or for thebleaching or dyeing of paper, but only the use I have described for theWILLIAM S. COLGROVE.

Witnesses:

DANIEL BROKA, EDWARD FRUSHER.

